Most modern railway cars include a pair of railway trucks with each railway truck having a pair of axles. Typically, a pair of wheels are secured to each axle with the wheels spaced from each other at a distance corresponding with the gauge of the railway trucks. A pair of roller bearing assemblies are generally mounted on the axle to reduce friction and to allow the axle and associated wheels to rotate with a minimum amount of applied force. A railway axle typically includes a shaft with a wheel seat and journal formed adjacent to opposite ends of the shaft. A wheel is secured to each wheel seat. An associated journal extends from each wheel seat for mounting a respective bearing assembly adjacent to each end of the railway axle. Each bearing assembly is preferably tightly fitted on its respective journal. Each bearing assembly includes a housing that receives a portion of a frame for an associated railway truck. The journals often have the smallest diameter of the railway axle and the wheel seats often have the largest diameter. Therefore, a railway car axle will often flex between the journals and respective wheel seats when the associated railway car is loaded. Movement or flexing of the axle between the bearing assembly and the associated wheel will ultimately result in fretting and failure of the axle.
In order to make the railroad industry more competitive with other modes of transportation various methods have been undertaken to reduce fretting and increase the fatigue life of axles for railway cars. Efforts include hardcoating the journal with a wear resistant metal or alloy, and modifying the bearing assembly connection and accompanying seals. Prior modifications have substantially increased the cost of the axle and bearing assembly or the installation of both.
Other efforts have included railway car axle modifications such as varying the size of the journals and wheel seats. Allowable modifications are limited due to standard American Association of Railroads (AAR) classifications which require interchangeability of component parts.